Filling of small features, such as vias and trenches, by copper electroplating is an essential part of the semiconductor manufacture process. It is well known, that the presence of organic substances as additives in the electroplating bath can be crucial in achieving a uniform metal deposit on a substrate surface and in avoiding defects, such as voids and seams, within the copper lines.
One class of additives are the so-called levelers. Levelers are used to provide a substantially planar surface over the filled features. In literature, a variety of different leveling compounds has been described. In most cases, leveling compounds are N-containing and optionally substituted and/or quaternized polymers.
U.S. Pat. No. 6,425,996 B1 discloses leveling agents comprising the reaction product of polyaminoamides and epihalohydrins, dihalohydrins and 1-halogen-2,3-propanediols, respectively.
EP 1978134 A1 discloses leveling agents comprising polyethoxylated polyamides or polyethoxylated polyaminoamides. In the examples the end groups are both polyalkoxylated with 25, 40 or 20 alkoxy repeating units.
WO 2011/064154 discloses leveling agents of the following formula

Unpublished international patent application No. PCT/IB2012/052727 discloses a composition comprising a polyaminoamide comprising an aromatic moiety being attached to or located within the polymeric backbone.
It is an object of the present invention to provide a copper electroplating additive having good leveling properties, in particular leveling agents capable of providing a substantially planar metal layer and filling features on the nanometer and on the micrometer scale without substantially forming defects, such as but not limited to voids, with a metal electroplating bath, in particular a copper electroplating bath.
It is a further object of the present invention to provide a copper electroplating bath cabable of depositing a low impurity metal layer.